In the chapters above we presented our views in a rather infor­mal set­ting, trying to show the philosophical importance and conse­quences of a realist attitude toward holes rather than spelling out a full-ﬂedged theory of holes.In this appendix we attempt to address this task more di­rectly by summarizing some basic tenets of our account in a rather systematic – though by no means complete – fashion. For convenience, we divide the presentation into four main sec­tions:(1) a preliminary ontological part, which introduces the basic binary relation “is a hole in (or through)” along with some rel­evant facts;(2) a mereo­logical part, which systematizes some funda­men­tal prin­ci­ples governing the interplay between the host-hole and the part-whole relations;(3) a topological part, which summa­rizes some basic facts con­cern­ing surfaces and the taxonomy of holes; and(4) a morphological part, focusing on the fact that ob­jects with holes constitute – as we have put it – the morphologi­cal mani­fold of ﬁl­lable things.

….

The underly­ing logic is deliberately left vague, as after all we think holes are ut­terly neutral in this respect. A preferred al­ternative is some sort of a free logic, where im­proper de­scrip­tions and other pos­sibly empty expres­sions can be admitted bona ﬁde; however, every­thing that follows could in prin­ciple be dealt with within the frame­work of a standard ﬁrst-order logic, with i treated as an im­proper symbol. In ad­di­tion, we as­sume familiarity with some ba­sic princi­ples of ex­ten­sional mereo­logy and topol­ogy.

In 1957, Hugh Everett III believed he had solved the infamous measurement problem in quantum mechanics by explaining probability as an illusion in an evolving, deterministic universe of universes. His “relative state” theory horrified Niels Bohr, who treated Everett’s doctoral thesis (written under the guidance of John Wheeler) with disbelief and scorn.

Everett’s theory was reborn as the “many worlds” interpretation of quantum mechanics in the 1970s. Yet despite his idea’s growing popularity, Everett never wrote another word about quantum mechanics. Instead, he worked on military operations research, designing nuclear missile targeting software. In this lecture, investigative journalist and Everett biographer Peter Byrne traces how Everett’s theory evolved over the course of his often-troubled life.